PowerEdge 2850 Memory Beep with new memory

I purchased a PowerEdge 2850 on ebay. After unpacking I loaded 6 brand new 2GB memory sticks.The machine looks flawless, no dust, etc.

Then I power on the server and hear a 1-3-2 beep code ("No memory installed", http://docs.us.dell.com/support/edocs/systems/pe2850/en/it/t1393c20.htm#wp1096121).

So I switch back to the 4 x 1GB the server came with and get the same beep code. I tried several more times with 2 x 1GB , 4 x 2GB with the same result.

Any ideas?

Thanks,

Josh